(1). Technical Field
This invention relates to the field of disk drives, in particular, to a method for absorbing unwanted vibrations and resonances in dynamic mechanisms, such as disk drives, is fabricated with an integral dynamic absorber that can be formed where the vibration is to be suppressed. The absorbing system is disposed at a predetermined location on a load beam suspension.
(2). Description of the Prior Art
The following two documents relate to methods dealing with vibration suppression of head suspension assemblies.
U.S. Pat. No. 4,932,019 issued Jun. 5, 1990 to A. Bessho describes a vibration absorbing member for reducing resonance energy in an optical disk drive, but it also is used in conjunction with a drive base and not a head suspension assembly as in the invention.
U.S. Pat. No. 4,703,470 issued Oct. 27, 1987 to Castagna, et al, discloses a dynamic absorber used in a disk drive, but the absorber described has a viscoelastic link element between the absorber base and absorber mass, and is only described as being used on the drive carriage or base casting.
It is well known that high speed mechanisms having moving parts are susceptible to damaging vibratory effects which reduce the expected life of the mechanism. As an example, disk drives which use actuators and associated suspensions for bidirectional accessing of data tracks of a rotating disk suffer from undesirable vibrations and resonances. In the past the designer would add visco-elastic dampers to the suspension. However, outgassing would often occur with visco-elastic dampers creating friction polymers on the slider/disk interface thereby causing premature failure of the disk drive system.
Furthermore, a major objective for improved performance of disk drives is to achieve reduction in the access time of the rotating disk. The access time is dependent upon the mass of the suspension assembly. Thus, it is desirable to reduce the mass of the suspension assembly. The reduction of mass, if not correctly accomplished, may in effect increase the access time due to the increased severity of the structural resonances of the suspension.
Several methods dealing with vibration absorbing devices have been employed in the past to damp unwanted resonance frequencies of dynamic operating mechanisms. The absorbing devices are designed to undergo a resonance at a predetemined frequency which is related to the undesired resonance frequency. Such prior art devices are overly sensitive when undergoing assembly and handling and are not considered reliable since they may fail mechanically during operation.
In a hard disk drive, typically a head slider is positioned by a head suspension assembly (HSA) over a magnetic disk to facilitate reading and writing of information to the disk. The constituent elements of standard HSAs include a swage plate, a resilient zone, a load beam, a flexure and a head slider. The swage plate is positioned at a proximal end of the load beam, adjacent to the resilient zone and is mounted to the suspension by means of a boss and by laser welding. The swage plate provides stiffness to the rear mount section and is configured for mounting the load beam to an actuator arm of a disk drive. The flexure is positioned at a distal end of the load beam. Mounted to the flexure is a head slider with a read/write orientation with respect to an associated disk.